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Civil Engineering/Concrete Cylindrical thin shell


QUESTION: I have a Cylindrical shell spanning 57.5' from traverses (solid diaphragms)and 33' perpendicularly.

1. If I design it in SAP 2000, do I have to model the solid diaphragm or can I assume the mesh points to be pinned there?

2. I also have edge beams so should I model them as normal beams?

3. My shell will be 2" in the center of the curve and 4" at the ends so can I assign the meshed area near the support as 4" slab and near the center as 2" slab.

4. Is there any simple of cross checking my design? Any excel sheets or simple methods?

5. Please also tell any other important issue to look into during modeling and designing of my shell in SAP2000.

ANSWER: Dear Ghulam Mustafa

Could you send me pictures of your model to help me to judge?


---------- FOLLOW-UP ----------

QUESTION: I have attached the picture please check.

Also tell If I have modeled my shell on sap2000 then how will I design my shell? Using Ast1 and Ast2 ?? Or using the Moments?? Please how to take moments or As from SAP 2000

Dear ghulam Mustafa

1- I don't use diaphragms where I can be more accurate using the real behavior of the structure.

2- The valley beams can be modelled normally.

3- You have to assign the proper shell elements where you need according to your shell properties.

4 and 5 - You would check a short section of the structure by hand, which may be done very easily through using the classic rules of structural analysis. In this model you can check the behavior of the shell under its weight force and no way to check the lateral behavior of the structure unless using the whole structure model in sap or other softwares. One another way is to use other software like stad parallel with sap.


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Babak Esmailzadeh Hakimi


I can answer questions in Structural Engineering, Earthquake Engineering, Project Management and Project Control topics!


I am experienced in the area of earthquake engineering in electrical power industry, i.e. Lifeline Earthquake Engineering. My focus has been on structural seismic design of power installations. Recently I have got involved in project management in the category of constructional engineering.

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Bs degree in Civil Engineering from Ferdowsi University ,1988, Mashhad Iran, Ms degree in Earthquake Engineering, Sharif University of Technology, 1993, Tehran, Iran

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